Flashcards in Pustules, ulcers and vesicles Deck (15):
small circumscribed pus filled elevation of the epidermis
- may be centred on hair follicles or interfollicular
- transient, often seen as crusts, epidermal collarettes or erosion
causes of pustules
- pyoderma most common in dogs (rare in cats)
- sterile diseases less common in general eg. drug eruptions, pemphigous folaceous (most common in cats), subcorneal pustular dermatosis, sterile eosinophilic pustulosis
Ddx pustules in dogs
- pyoderma (neutrophils and cocci)
- pemphigus folaceous (neutrophils and free epithelial cells)
- drug eruption (variable)
- subcorneal pustular dermatosis (neutrophils but no bacteria)
- sterile eosinophilic pustulossis (eosinophils)
- juvenile cellulitits (neutrophils and macrophages)
Approach to pustules in dogs?
> if consistent with pyoderma, tx Abx and reexamine 10-20d
- skin scrap to r/o demodex
> if no response to Abx/cytology not consistnet
- culture and sesitivity for bacteria (suspect resistnace?)
- skin biopsies to dx all sterile pustular diseases
Apporoach to pustules in cats and horses?
- biopsy all cases (v unusual in these spp)
- Abx tx pending results
Ddx crusting in dogs and horses other than pustules?
- dermatophytes (dogs)
- dermatophilis congolensis (horses)
Define ulceration. Causes?
-break in the continuity of the epidermis to expose underlying dermis
- consequence of self trauma w/ pruritis
- consequence of disease of epidermis/epidermo-dermal junction (infections/autoimmune/drug reactions/neoplasia)
- widespread may reflect progression from vesicles (intraepidermal vesicular dermatitides) and bullae (subepidermal vesicular dermatitides), epidermal separation (interface dermatitis) or epithelioptrophic lymphoma
Prognosis of epithelioptrophic lymphoma?
- poor despite tx
- epidermis damaged by invasion of neoplastic lymphocytes
Workup of ulcerative skin disease?
Biopsy routinely as may ddx severe and need aggressive tx
- intact 1* lesions best
- excisional biopsy across margins of lesions (if you only biopsy the ulcer, pathologist will tell you its an ulcer!)
What are vesicles?
- fluid filled elevations of the skin LESS THAN 1cm in diameter (Bulla if >1cm)
- transient in haired skin due to thin epidermis
- histo: intra-epidermal/subepidermal vesicular dermatitis or interface dermatitis
Aetiology of vesicles?
- irritant chemicals/burns
- auto-immune/immune mediated disease
> NB: FMD notifiable in farm animals causes vesicles
are drug reactions the same as drug side effects?
NO drug reactions immune mediated, drug side effects direct result of chemicals
egs. drug reaction presentations
- urticaria and angioedema
- exfoliative erythroderma (red scaly skin)
- autoimmune presentation
Dx drug reaction?
- hx drug exposure
- clinical signs of drug reaction
- r/o other causes
> do not rechallenge with offedning drug!!!